An early step in the atherosclerotic process is focal expression on the vascular endothelium of vascular adhesion molecule-1(VCAM- 1), a monocyte-specific adhesion molecule. The factors which lead to the expression of leukocyte adhesion molecules and the subsequent leukocyte accumulation are unknown. In this proposal, the canidate presents preliminary evidence that the catabolism of the circulating liporprotein VLDL by its normal enzyme, lipoprotein lipase (LPL), induces the expression of VCAM-1 on the surface of endothelial cells. LPL is able to incuse both extracellular lipolysis as well as receptor-mediated endocytosis of VLDL, thugh which is responsible for VCAM-1 induction is unknown. The goal of this prpoosal is to investigate and characterize both the consequences and mechanisms underlying the endothelial expression of leukocyte adhesion molecules induced by the LPL-mediated catabolism of VLD. To accomplish this, he proposes to: 1) Analyze the induction of VCAM-1, as well as other well known leukocyte adhesion molecules (i.e. E-Selectin, P-Selectin and ICAM-1) by the lipolysis of VldL in vitro. Both the proten and mRNa levels will be measured. Transcriptional activation will be confirmed by nuclear runoff analysis; 2) The functional contributions of increased adhesion molecular expression will be assessed by measuring monocyte adhesion under both flow and static conditions. Functional contributions of molecules identified above will be confirmed by the use of specific function-blocking antibodies; 3) Extracellular lipolysis will be evluated using a mutant of LPL (LPLC) which lacks the catalytic domain but still induces receptor- mediated catabolism of lipoproteins; 4) Receptor-mediated catabolism will also be evaluated using well-established inhibitors including LPLCww, the 39 kD receptor-associated protein (RAP) and antibodies to LDL and VLDL receptors; and 5) Products of lipolysis will be fractionated and isolated using TLC and HPLC and for assessed bioactivity using techniques described in # 1.